Magnetoresistive stack with seed region and method of manufacturing the same

ABSTRACT

A magnetoresistive stack/structure and method of manufacturing same comprising wherein the stack/structure includes a seed region, a fixed magnetic region disposed on and in contact with the seed region, a dielectric layer(s) disposed on the fixed magnetic region and a free magnetic region disposed on the dielectric layer(s). In one embodiment, the seed region comprises an alloy including nickel and chromium having (i) a thickness greater than or equal to 40 Angstroms (+/−10%) and less than or equal to 60 Angstroms (+/−10%), and (ii) a material composition or content of chromium within a range of 25-60 atomic percent (+/−10%) or 30-50 atomic percent (+/−10%).

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. application Ser. No.15/373,880, filed Dec. 9, 2016, which claims the benefit of U.S.Provisional Application No. 62/265,650, filed Dec. 10, 2015, both ofwhich are incorporated herein by reference in their entireties. Further,this application claims the benefit of U.S. Provisional Application No.62/712,578, filed Jul. 31, 2018, which is incorporated herein byreference in its entirety.

TECHNICAL FIELD

The present disclosure relates to, among other things, magnetoresistivestacks and methods of manufacturing magnetoresistive stacks. Morespecifically, embodiments of the present disclosure are directed tomagnetoresistive stacks including one or more seed regions, and methodsof manufacturing magnetoresistive stacks including one or more seedregions.

INTRODUCTION

There are many inventions described and illustrated herein, as well asmany aspects and embodiments of those inventions. In one aspect, thepresent inventions relate to a magnetoresistive stack/structure (forexample, a magnetoresistive memory stack/structure or a magnetoresistivesensor/transducer stack/structure) and a method of manufacturing such astack/structure. In one embodiment of this aspect of the invention, theinventive magnetoresistive stack/structure (for example, a magnetictunnel junction (MTJ) stack/structure) includes a seed region having amaterial composition and an associated thickness, disposed between anelectrically conductive material (for example, a metal of anelectrode/via/line) and a region including one or more layers ofmagnetic or ferromagnetic materials, that improves the reliability,thermal stability and/or thermal endurance of the magnetoresistivestack/structure.

For example, the seed region may include one or more of nickel,chromium, cobalt, iron and alloys thereof (for example, an alloyincluding nickel and/or chromium) having a thickness which is greaterthan or equal to 30 Angstroms, or 40 Angstroms, or 50 Angstroms, orpreferably greater than or equal to 60 Angstroms, or more preferablygreater than or equal to 40 or 50 Angstroms and less than or equal to100 Angstroms (for example, 40 Angstroms to 60 Angstroms), or even morepreferably greater than or equal to 60 Angstroms and less than or equalto 100 Angstroms, or most preferably 60 Angstroms +/−10%. The seedregion may be disposed between and in physical contact with anelectrically conductive metal material of an electrode/via/line (forexample, in the context of an electrode or via, tantalum, or an alloythereof (such as a tantalum-nitride alloy), or a composite thereof (suchas a tantalum and tantalum-nitride alloy composite)) and the fixedmagnetic region a magnetoresistive memory stack/structure (which, in oneembodiment, includes a plurality of layers of one or more magnetic orferromagnetic materials (for example, a multi-layer structure of (i)cobalt and platinum or (ii) cobalt and nickel)).

In one embodiment, the seed region is implemented in a MTJ-typemagnetoresistive stack/structure having a perpendicular magneticanisotropy wherein the magnetic region disposed on or in physicalcontact with the seed region maintains or includes improved properties(for example, magnetoresistance (MR) and resistance-area product (RA) ofthe stack/structure) after subsequent or additional processing (forexample, annealing processes after deposition/formation of the magneticregion). Indeed, a stack/structure including such a seed region mayexhibit improved reliability, thermal stability and/or thermal enduranceof the magnetoresistive stack/structure, for example, a magnetoresistivememory stack/structure. Here, the seed region of the present inventionsmay facilitate growth thereon of layers of the magnetic region that aresmoother and/or include sharper interfaces (relative to layers grown onconventional seed regions). For example, a multi-layer magnetic region(e.g., (i) cobalt and platinum or (ii) cobalt and nickel) may be grownon the seed region of the present inventions more smoothly and withsharper interface. Further, the seed regions of the present inventionsmay include less stress (again relative to layers grown on conventionalseed regions). One, some or all of these characteristics may facilitatean MTJ-type magnetoresistive stack/structure of the present inventionsto include and/or maintain improved characteristics or properties (forexample, magnetoresistance (MR) and resistance-area product (RA) of thestack/structure) even after being undergoing one or more annealprocesses at elevated temperatures (for example, 400° C.).

Notably, the present inventions may employ any technique now known orlater developed to manufacture the MTJ stack/structure including withrespect to the formation and/or deposition of the seed region; all suchtechniques are intended to fall within the scope of the presentinventions. For example, in one embodiment, the seed region is an alloyincluding nickel and chromium and is formed or deposited, via ion-beamdeposition, sputtering and/or evaporation techniques, on an electricallyconductive metal of, for example, an electrode/via/line (for example, ametal material such as tantalum or tantalum-nitride, or a compositethereof). Thereafter, one or more layers of ferromagnetic material (forexample, a multi-layer structure of (i) cobalt and platinum or (ii)cobalt and nickel) may be deposited on the seed region. The multi-layerstructure of cobalt and platinum may start with a cobalt layer (followedby a platinum layer) disposed on the nickel and chromium alloy seedlayer/region. Where the multi-layer structure is cobalt and nickel, anickel layer/region (followed by a cobalt layer) may be first disposedon the nickel and chromium alloy seed layer.

Briefly, a magnetoresistive memory stack/structure, in one embodiment,includes at least one non-magnetic layer (for example, at least onedielectric layer) disposed between a “fixed” magnetic region and a“free” magnetic region, each consisting of a plurality of layers of oneor more magnetic or ferromagnetic materials. Information is stored inthe magnetoresistive memory stack/structure by switching, programmingand/or controlling the direction of magnetization vectors in one or moreof the magnetic layers of the free magnetic region of thestack/structure. Here, the direction of the magnetization vectors of thefree magnetic region may be switched and/or programmed (for example,through spin-torque transfer) by application of a write signal (one ormore current pulses) to or through the magnetoresistive memorystack/structure while, in contrast, the magnetization vectors in themagnetic layers of a fixed magnetic region are magnetically fixed (in apredetermined direction).

The magnetoresistive memory stack/structure includes an electricalresistance that depends on the magnetic state of certain regions of thememory stack/structure. That is, in one embodiment, when themagnetization vectors of the “free” magnetic region are in a first stateor in a first direction (for example, which is the same direction as thedirection of the magnetization vectors of the “fixed” magnetic region),the magnetoresistive memory stack/structure has a first magnetic statewhich may correspond to a low electrical resistance state. Conversely,when the magnetization vectors of the “free” magnetic region are in asecond state or in a second direction (for example, which is a differentdirection (for example, opposite or opposing) as the direction of themagnetization vectors of the “fixed” magnetic region), themagnetoresistive memory stack/structure has a second magnetic statewhich may correspond to a high electrical resistance state. The magneticstate of the magnetoresistive memory stack/structure is determined orread based on the resistance of the magnetoresistive memorystack/structure in response to a read current of a read operation.

As intimated above, the present inventions are directed to amagnetoresistive stack/structure—for example, a magnetoresistive memorystack/structure or a magnetoresistive sensor/transducer stack/structurehaving a seed region (which includes, for example, an alloy includingnickel and chromium having a thickness (T) of T≥30 Angstroms +/−10%, orT≥40 Angstroms +/−10%, or ≥50 Angstroms +/−10%, or preferably T≥60Angstroms +/−10%, or more preferably 100 Angstroms≥T≥40 or 50 Angstroms(each limit +/−10%) (for example, 60 Angstroms≥T≥40 Angstroms), or evenmore preferably 100 Angstroms≥T≥60 Angstroms (each limit +/−10%) (forexample, T=80 Angstroms +/−10%), or most preferably T=60 Angstroms+/−10%), disposed between and in physical contact with an electricallyconductive material such as metal of, for example, an electrode/via/lineand a region having one or more layers of magnetic or ferromagneticmaterials (for example, a fixed magnetic region of a magnetoresistivememory stack/structure). Further, the seed region may be substantiallynon-magnetic having a material composition or content including an alloyincluding nickel, iron, cobalt and/or chromium (for example, in oneembodiment, an alloy including nickel and chromium wherein 25-60 atomicpercent (+/−10%) or 30-50 atomic percent (+/−10%) is chromium, andpreferably 40 atomic percent (+/−10%) is chromium).

The present inventions are also directed to magnetoresistive integratedcircuit devices (for example, a spin-torque MRAM) having one or moremagnetoresistive stacks/structures (for example, a plurality of MTJstacks/structures of a MTJ-based sensor/transducer device and/orMTJ-based memory device). In one embodiment, the MTJ stacks/structurespossess/include a perpendicular magnetic anisotropy wherein the magneticregion disposed on or in physical contact with the inventive seed regionmaintains or includes improved properties or characteristics (forexample, magnetoresistance (MR) and resistance-area product (RA) of thestack/structure) after processing (for example, one or more annealingprocesses after deposition/formation of the magnetic region). Indeed, amagnetoresistive stack/structure including such a seed region may bemore reliable and thermally stable and/or provide greater thermalendurance.

Notably, although certain exemplary embodiments are described and/orillustrated herein in the context of MTJ stacks/structures, the presentinventions may be implemented in giant magnetoresistive (GMR)stacks/structures where a conductor is disposed between twoferromagnetic materials. Indeed, the present inventions may be employedin connection with other types of magnetoresistive stacks/structureswherein such stacks/structures include a seed region which is disposedbetween and in physical contact with an electrically conductiveelectrode/via/line and a region having one or more layers of magnetic orferromagnetic materials. For the sake of brevity the discussions andillustrations will not be repeated specifically in the context of GMR orother magnetoresistive stacks/structures—but such discussions andillustrations are to be interpreted as being entirely applicable to GMRand other stacks/structures.

BRIEF DESCRIPTION OF THE DRAWINGS

The present inventions may be implemented in connection with embodimentsillustrated in the attached drawings. These drawings show differentaspects of the present inventions and, where appropriate, referencenumerals illustrating like structures, components, materials and/orelements in different figures are labeled similarly. It is understoodthat various combinations of the structures, components, and/orelements, other than those specifically shown, are contemplated and arewithin the scope of the present inventions.

Moreover, there are many inventions described and illustrated herein.The present inventions are neither limited to any single aspect norembodiment thereof, nor to any combinations and/or permutations of suchaspects and/or embodiments. Moreover, each of the aspects of the presentinventions, and/or embodiments thereof, may be employed alone or incombination with one or more of the other aspects of the presentinventions and/or embodiments thereof. For the sake of brevity, certainpermutations and combinations are not discussed and/or illustratedseparately herein. Notably, an embodiment or implementation describedherein as “exemplary” is not to be construed as preferred oradvantageous, for example, over other embodiments or implementations;rather, it is intended reflect or indicate the embodiment(s) is/are“example” embodiment(s).

FIGS. 1A and 1B each illustrate a cross-sectional view of layers of anexemplary MTJ-type magnetoresistive stack/structure (for example, anin-plane or out-of-plane (e.g., perpendicular) magnetic anisotropymagnetoresistive stack/structure) including a dielectric layer disposedbetween a free magnetic region and a fixed magnetic region wherein, inthis exemplary embodiment, the fixed magnetic region is disposed on theseed region according to certain aspects of certain embodiments of thepresent inventions wherein the seed region includes one or more ofnickel, chromium, cobalt and iron and alloys thereof, for example, analloy including nickel and/or chromium, having a thickness (T) of T≥30Angstroms, T≥40 Angstroms, or T≥40 Angstroms, or preferably T≥60Angstroms, or more preferably 100 Angstroms≥T≥40 or 50 Angstroms, oreven more preferably 100 Angstroms≥T≥60 Angstroms(for example, T=80Angstroms), or most preferably T=60 Angstroms (notably, each of theaforementioned values, limits or ranges may be +/−10%); in thisexemplary embodiment, the MTJ-type magnetoresistive stack/structure isdisposed between and in physical contact with electrically conductiveelectrodes/vias/lines (for example, in the context of an electrodes orvias, tantalum, or an alloy thereof (such as a tantalum-nitride alloy),or a composite thereof (such as a tantalum and tantalum-nitride alloycomposite)); notably, the free magnetic region and the fixed magneticregion may each include a plurality of the layer(s) of magnetic orferromagnetic material(s) (for example, materials that include one ormore of the ferromagnetic elements nickel (Ni), iron (Fe), and cobalt(Co), including, for example, alloys or engineered materials with one ormore of the elements palladium (Pd), platinum (Pt), magnesium (Mg),manganese (Mn), and chromium (Cr)) as well as one or more syntheticantiferromagnetic structures (SAF) or synthetic ferromagnetic structures(SyF) wherein one or more layers of magnetic materials layers may alsoinclude one or more non-magnetic materials layers (for example,ruthenium (Ru), copper (Cu), aluminum (Al), tantalum (Ta), titanium(Ti), niobium (Nb), vanadium (V), zirconium (Zr), iridium (Ir) and oneor more alloys thereof, and in certain embodiments, tungsten (W) andmolybdenum (Mo); moreover, the dielectric layers may be, for example,one or more layers of aluminum oxide and/or magnesium oxide;

FIGS. 2A and 2B are simplified exemplary manufacturing flows for thedeposition of layers of the exemplary MTJ-type magnetoresistivestack/structures of FIGS. 1A and 1B, respectively, according to certainaspects of certain embodiments of the present inventions wherein thevarious layers and/or regions are sequentially deposited, grown,sputtered, evaporated, formed and/or provided (hereinafter collectively“deposited” or other verb tense (e.g., “deposit” or “depositing”)) toprovide the material stack that, after further processing, will be anMTJ-type magnetoresistive stack/structure (for example, having aperpendicular magnetic anisotropy);

FIG. 3A illustrates a cross-sectional view of an exemplary fixedmagnetic region wherein in one exemplary embodiment, the fixed magneticregion is a fixed, unpinned SAF including a first multi-layer structure(AP1) which is antiferromagnetically coupled to a second multi-layerstructure (AP2) via the coupling layer wherein each multi-layerstructure may include a plurality of layers of magnetic or ferromagneticmaterial(s) (for example, materials that include one or more of theferromagnetic elements nickel (Ni), iron (Fe), and cobalt (Co),including alloys or engineered materials with one or more of theelements palladium (Pd), platinum (Pt), chromium (Cr) and alloysthereof); the coupling layer may include one or more non-magneticmaterials (for example, ruthenium (Ru), iridium (Ir) or rhodium (Rh));

FIG. 3B illustrates a cross-sectional view of an exemplary magneticmulti-layer of a portion of a fixed, unpinned SAF region of, forexample, a fixed magnetic region, having interface layers (for example,layers that are in contact or interface with the seed region, thecoupling layer and/or the dielectric layer), according to certainembodiments of the present inventions; notably, the magnetic multi-layerstructure may be employed as AP1 and/or AP2 of the fixed, unpinned SAFregion (see, for example, FIG. 3A) of, for example, a fixed magneticregion; moreover, the magnetic multi-layer structure may include one ormore insertion layers (for example, one or more non-ferromagnetictransition metals, such as tantalum (Ta), tungsten (W) and/or molybdenum(Mo))—albeit such insertion layer(s) is/are not illustrated;

FIG. 3C illustrates a cross-sectional view of another exemplary fixedmagnetic region including multi-layer structures (AP1 or AP2) and atransition layer and a reference layer disposed between AP2 and thedielectric layer, according to certain embodiments of the inventions,wherein the transition layer may include one or more layers of materialthat facilitate/improve growth of the dielectric layer (which is atunnel barrier in the MTJ structure) during fabrication; in oneembodiment, the reference layer may include one or more or all ofcobalt, iron, boron and tantalum (for example, in an alloy—such as anamorphous alloy (e.g., CoFeB or CoFeBTa or CoFeTa) and the transitionlayer may include a non-ferromagnetic transition metal such as tantalum,titanium, tungsten and/or molybdenum; in another embodiment, thereference layer may include a layer of iron (for example, deposited aspure or substantially pure iron) and a layer of cobalt, iron and boron(for example, deposited as an alloy) wherein, after further/finalprocessing (e.g., after annealing), the layer of iron at the interfacemay form a continuous atomic layer or may mix with the underlyingferromagnetic alloy in the final annealed structure, resulting in ahigh-iron interface region within the reference layer which is adjacentto the dielectric layer;

FIG. 4A illustrates a cross-sectional view of an exemplary free magneticregion wherein in one exemplary embodiment, the free magnetic regionincludes a plurality of ferromagnetic layers and one or more insertionlayers (for example, having one or more non-ferromagnetic transitionmetals, such as tantalum, niobium, vanadium, zirconium, molybdenum orruthenium and/or one or more alloys thereof); in one embodiment, thefree magnetic region may include alternating ferromagnetic layers (forexample, having cobalt, iron, boron, nickel and/or one or more alloysthereof such as a cobalt-iron alloy or a cobalt-iron-boron alloy) andinsertion layers (for example, having one or more non-ferromagnetictransition metals, such as tantalum, niobium, vanadium, zirconium,molybdenum or ruthenium and/or one or more alloys thereof); notably, inone embodiment, the alternating ferromagnetic layer—insertion layerstructure is disposed between ferromagnetic interface regions (forexample, iron or an iron alloy) which interface with and/or contact thedielectric layer (i.e., tunnel barrier of the magnetoresistivestack/structure) and the spacer region (see FIG. 1A) or the first andsecond dielectric layers (see FIG. 1B);

FIG. 4B illustrates a cross-sectional view of an exemplary free magneticregion wherein in one exemplary embodiment, the free magnetic regionincludes a plurality of ferromagnetic materials and/or layers (forexample, cobalt, iron, nickel and/or one or more alloys thereof such asa cobalt-iron alloy or a cobalt-iron-boron alloy); in this embodiment,the free magnetic region does not include one or more insertion layersin an alternating ferromagnetic layer - insertion layer structure(albeit, in one embodiment, not all insertion layers are omitted fromthe free magnetic region); notably, in this embodiment, the freemagnetic region may also include ferromagnetic interface regions (forexample, for example, iron or an iron alloy) which interface with and/orcontact the dielectric layer (i.e., tunnel barrier of themagnetoresistive stack/structure) and the spacer region (see FIG. 1A) orthe first and second dielectric layers (see FIG. 1B);

FIGS. 5A-5B illustrate cross-sectional views depicting various regionsof exemplary magnetoresistive stacks, according to one or moreembodiments of the present disclosure;

FIGS. 6A-6F illustrate cross-sectional views depicting exemplary seedregions of the exemplary magnetoresistive stacks depicted in FIGS.5A-5B;

FIG. 7 illustrates a cross-sectional view depicting exemplary layers ofa SAF disposed above an exemplary seed region within themagnetoresistive stacks shown in FIGS. 5A-5B;

FIG. 8 is a flow chart illustrating an exemplary fabrication process formanufacturing a magnetoresistive device, according to one or moreembodiments of the present disclosure;

FIG. 9 is a flow chart illustrating another exemplary fabricationprocess for manufacturing a magnetoresistive device, according to one ormore embodiments of the present disclosure;

FIG. 10 is an exemplary schematic diagram of a magnetoresistive memorystack/structure electrically connected to an access transistor in amagnetoresistive memory cell configuration; and

FIGS. 11 and 12 are schematic block diagrams of integrated circuitsincluding discrete memory device and an embedded memory device, eachincluding MRAIVI (which, in one embodiment is representative of one ormore arrays of MRAIVI having a plurality of magnetoresistive memorystacks/structures according to according to certain aspects of certainembodiments of the present inventions.

Again, there are many inventions described and illustrated herein. Thepresent inventions are neither limited to any single aspect norembodiment thereof, nor to any combinations and/or permutations of suchaspects and/or embodiments. Each of the aspects of the presentinventions, and/or embodiments thereof, may be employed alone or incombination with one or more of the other aspects of the presentinventions and/or embodiments thereof. For the sake of brevity, many ofthose combinations and permutations are not discussed separately herein.

Moreover, many other aspects, inventions and embodiments, which may bedifferent from and/or similar to, the aspects, inventions andembodiments illustrated in the drawings, will be apparent from thedescription, illustrations and claims, which follow. In addition,although various features and attributes have been illustrated in thedrawings and/or are apparent in light thereof, it should be understoodthat such features and attributes, and advantages thereof, are notrequired whether in one, some or all of the embodiments of the presentinventions and, indeed, need not be present in any of the embodiments ofthe present inventions.

Notably, for simplicity and clarity of illustration, certain aspects ofthe figures depict the general structure and/or manner of constructionof the various embodiments. Descriptions and details of well-knownfeatures and techniques may be omitted to avoid unnecessarily obscuringother features. Elements in the figures are not necessarily drawn toscale; the dimensions of some features may be exaggerated relative toother elements to improve understanding of the example embodiments. Forexample, one of ordinary skill in the art appreciates that thecross-sectional views are not drawn to scale and should not be viewed asrepresenting proportional relationships between different layers. Thecross-sectional views are provided to help illustrate the processingsteps performed by simplifying the various layers to show their relativepositioning. Moreover, while certain layers and features are illustratedwith straight 90-degree edges, in actuality or practice such layers maybe more “rounded” and gradually sloping.

DETAILED DESCRIPTION

The following Detailed Description is merely illustrative and is notintended to limit the embodiments of the subject matter or theapplication and uses of such embodiments. Any embodiment orimplementation described herein as exemplary is not necessarily to beconstrued as preferred or advantageous over other implementations.Rather it is intended or used in the sense of an “example” rather than“ideal” or “preferred” or “advantageous” relative to otherimplementations or embodiments.

Further, the terms “comprise,” “include,” “have” and any variationsthereof are used synonymously to denote or describe non-exclusiveinclusion.As such, a process, method, article, or apparatus that usessuch terms does not include only those steps, structure or elements butmay include other steps, structures or elements not expressly listed orinherent to such process, method, article, or apparatus. In addition,the terms “first,” “second,” and the like, herein do not denote anyorder, quantity, or importance, but rather are used to distinguish anelement, a structure, a step or a process from another. Moreover, theterms “a” and “an” herein do not denote a limitation of quantity, butrather denote the presence of at least one of the referenced item.

In one aspect, the present inventions relate to a magnetoresistivestack/structure (for example, a magnetoresistive memory stack/structureor a magnetoresistive sensor/transducer stack/structure) and a method ofmanufacturing such a stack/structure wherein the magnetoresistivestack/structure (for example, a magnetic tunnel junction (MTJ)stack/structure) includes a seed region having a material compositionand an associated thickness that improves the reliability, thermalstability and/or thermal endurance of the magnetoresistivestack/structure. For example, the seed region may include one or more ofnickel, chromium, cobalt, iron and alloys thereof (for example, an alloyincluding nickel and/or chromium) having a thickness which is greaterthan or equal to 30 Angstroms or 40 Angstroms or 50 Angstroms,preferably greater than or equal to 60 Angstroms and less than or equalto 100 Angstroms (for example, 80 Angstroms), or most preferably 60Angstroms (notably, each of the aforementioned values, limits and/orranges of the thickness of the seed region may be +/−10%), which isdisposed between and in physical contact with an electrically conductivematerial (for example, a metal material of, for example, anelectrode/via/line (for example, in the context of an electrode or via,tantalum, or an alloy thereof or a composite thereof and the fixedmagnetic region a magnetoresistive memory stack/structure (which, in oneembodiment, includes a plurality of layers of one or more magnetic orferromagnetic materials (for example, a multi-layer structure of (i)cobalt and platinum or (ii) cobalt and nickel))).

In one embodiment, the seed region is implemented in a MTJ-typemagnetoresistive stack/structure having a perpendicular magneticanisotropy wherein the magnetic region, which is disposed on or inphysical contact with the seed region, maintains or includes improvedproperties (for example, magnetoresistance (MR) and resistance-areaproduct (RA) of the stack/structure) after subsequent or additionalprocessing (for example, annealing processes at temperatures of 400°C.)). Indeed, a stack/structure including such a seed region may exhibitimproved reliability, thermal stability and/or thermal endurance of themagnetoresistive stack/structure. Here, the seed region of the presentinventions may facilitate growth thereon of layers of the magneticregion that are smoother and/or include sharper interfaces (relative tolayers grown on conventional seed regions). For example, a multi-layermagnetic region (e.g., (i) cobalt and platinum or (ii) cobalt andnickel) may be grown on the seed region of the present inventions moresmoothly and with sharper interface. Further, the seed regions of thepresent inventions may include less stress (again relative to layersgrown on conventional seed regions). One, some, or all of thesecharacteristics may contribute to an MTJ-type magnetoresistivestack/structure exhibiting and/or maintaining improved characteristicsor properties (for example, magnetoresistance (MR) and resistance-areaproduct (RA) of the stack/structure) even after undergoing or beingexposed to one or more processes (for example, one or more annealprocesses) at elevated temperatures (for example, 400° C.).

For the sake of brevity, conventional techniques related tosemiconductor processing may not be described in detail herein. Theexemplary embodiments may be fabricated using known lithographicprocesses. The fabrication of integrated circuits, microelectronicdevices, micro electro mechanical devices, microfluidic devices, andphotonic devices involves the creation of several layers of materialsthat interact in some fashion. One or more of these layers may bepatterned so various regions of the layer have different electrical orother characteristics, which may be interconnected within the layer orto other layers to create electrical components and circuits. Theseregions may be created by selectively introducing or removing variousmaterials. The patterns that define such regions are often created bylithographic processes. For example, a layer of photoresist is appliedonto a layer overlying a wafer substrate. A photo mask (containing clearand opaque areas) is used to selectively expose the photoresist by aform of radiation, such as ultraviolet light, electrons, or x-rays.Either the photoresist exposed to the radiation, or that not exposed tothe radiation, is removed by the application of a developer. An etch maythen be employed/applied whereby the layer not protected by theremaining resist is patterned. Alternatively, an additive process can beused in which a structure is built up using the photoresist as atemplate.

As noted above, in one aspect, the described embodiments relate to,among other things, methods of manufacturing a magnetoresistivestack/structure having one or more electrically conductive electrodes,vias or conductors on either side of a magnetic material stack. Asdescribed in further detail below, the magnetic material stack mayinclude many different layers of material, where some of the layersinclude magnetic materials, whereas others do not. In one embodiment,the methods of manufacturing include sequentially depositing, growing,sputtering, evaporating and/or providing (as noted above, hereinaftercollectively “depositing” or other verb tense (e.g., “deposit” or“deposited”)) layers and regions which, after further processing (forexample, etching) those layers form a magnetoresistive stack/structure.

The magnetoresistive structures/stacks of the present inventions may beformed between electrically conductive material of, for example, a topelectrode/via/line and a bottom electrode/via/line, which permit accessto the stack/structure by allowing for connectivity to circuitry andother elements of the magnetoresistive device. Between electricallyconductive material of, for example, the electrodes/vias/lines, arelayers and/or regions, including at least one fixed magnetic region(which includes, among other things, a plurality of ferromagneticlayers), a seed region, which in at least one embodiment is disposedbetween the electrically conductive electrode/via/line, at least onefree magnetic region (which includes, among other things, a plurality offerromagnetic layers), and one or more dielectric layers or regions(hereinafter collectively, “dielectric layer”—including at least onedielectric layer, disposed between a fixed magnetic region and the freemagnetic region, to provide a tunnel barrier layer therebetween.

With reference to FIGS. 1A, 1B, 2A and 2B, the magnetoresistivestructure/stack of a first aspect of the present inventions includes aseed region that is deposited on electrically conductive material of anelectrode, via and/or conductor. In one embodiment, the material of theseed region includes one or more of nickel, chromium, cobalt, iron andalloys thereof. Here, the seed region may be deposited using a physicalvapor deposition technique (for example, a sputtering technique (suchas, an ion beam deposition or magnetron sputtering) and/or anevaporation technique. For example, the material of the seed region maybe a nickel-chromium alloy which is ion beam sputtered on the materialof the electrically conductive material (for example, a metal materialof an electrode, via and/or conductor (for example, tantalum, or analloy thereof (such as a tantalum-nitride alloy), or a composite thereof(such as a tantalum and tantalum-nitride alloy composite)). In oneembodiment, the content of chromium is sufficient to render the seedregion non-magnetic. For example, the nickel-chromium alloy may begreater than or equal to 25 or 30 atomic percent (+/−10%) chromium andless than or equal to 50 or 60 atomic percent (+/−10%) chromium andpreferably, 40 atomic percent (+/−10%) chromium; notably, the balance ofthe nickel-chromium alloy, in one embodiment, consists of nickel.

With continued reference to FIGS. 1A, 1B, 2A and 2B, the thickness ofthe material (for example, nickel-chromium alloy) of the seed region, inone embodiment, is greater than or equal to 30, 40 or 50 Angstroms, orpreferably greater than or equal to 60 Angstroms. In one embodiment, thethickness of the material of the seed region is greater than or equal to40 Angstroms and less than or equal to 100 Angstroms (for example,greater than or equal to 40 Angstroms and less than or equal to 60Angstroms), or preferably greater than or equal to 60 Angstroms and lessthan or equal to 100 Angstroms (for example, 80 Angstroms). In a mostpreferred embodiment, the thickness of the material (for example, anickel-chromium alloy) of the seed region is 60 Angstroms. In thecontext of a nickel-chromium alloy, all combinations of theaforementioned thicknesses in conjunction with the aforementioned nickeland chromium atomic percentages are intended to fall within the scope ofthe present inventions (for example, Ni₆₀Cr₄₀ atomic percent having athickness greater than or equal to 40 Angstroms and more preferably, (i)equal to 60 Angstroms or (ii) greater than or equal to 40 Angstroms andless than or equal to 60 Angstroms). Notably, each of the aforementionedvalues, limits and/or ranges of the thickness of the seed region may be+/−10%.

After deposition of the seed region, a fixed magnetic region isdeposited. The fixed magnetic region may be a multi-layer, unpinned SAFincluding a plurality of layers of one or more magnetic or ferromagneticmaterials (for example, a multi-layer structure of (i) cobalt andplatinum (for example, each layer having a thickness of 5 Angstroms orless, preferably 4 Angstroms or less, and more preferably having athickness of 3 Angstroms or less) or (ii) cobalt and nickel (forexample, each layer having a thickness between 1 and 6 Angstroms,preferably 4 Angstroms or less, and more preferably 3 Angstroms orless)) separated by a coupling layer (for example, a coupling layerincluding ruthenium having a thickness of, for example, 4 Angstroms(+/−1 Angstrom)). (See, for example, FIGS. 3A and 3B).

The fixed magnetic region may be deposited or formed using any techniquenow known or later developed; all of which are intended to fall withinthe scope of the present inventions.

Notably, where the multi-layer SAF of the fixed magnetic region iscobalt and platinum an initial layer of ferromagnetic material of cobaltmay be deposited on the seed region. Where the multi-layer SAF of thefixed magnetic region is cobalt and nickel, an initial layer offerromagnetic material of nickel may be deposited on the seed region.Moreover, the multilayer SAF may include cobalt layers at bothinterfaces with the coupling layer.

Indeed, in one embodiment, the multilayer SAF of the fixed magneticregion possesses a perpendicular magnetic anisotropy. The seed region ofthe present inventions may facilitate growth, deposition or formation ofan MTJ-based stack/structure having a perpendicular magnetic anisotropywith improved thermal endurance and properties notwithstandingsubsequent or additional processing —including annealing processes of400° C. Here, the seed region may facilitate growth, deposition orformation of smoother layers having a sharper interface. Such growth,deposition or formation may also provide less stress thereby assistingin the maintenance of high MR post processing at elevated temperatures(for example, 400° C.).

With reference to FIG. 3C, in another embodiment, the fixed magneticregion includes multi-layer structures (AP1 or AP2) and a transitionlayer and a reference layer disposed between AP2 and the dielectriclayer. The transition layer may include one or more layers of materialthat facilitate/improve growth of a dielectric layer (which may be thetunnel barrier in the MTJ stack/structure) during fabrication. In oneembodiment, the reference layer may include one or more or all ofcobalt, iron, boron and tantalum (for example, in an alloy—such as anamorphous alloy (e.g., CoFeB or CoFeBTa or CoFeTa)) and the transitionlayer may include a non-ferromagnetic transition metal such as tantalum,titanium, tungsten and/or molybdenum. In yet another embodiment, thereference layer may include a layer of iron (for example, deposited aspure or substantially pure iron) and a layer of cobalt, iron and boron(for example, deposited as an alloy) wherein, after further/finalprocessing (e.g., after annealing), the layer of iron at the interfacemay form a continuous atomic layer or may mix with the underlyingferromagnetic alloy in the final annealed structure, resulting in ahigh-iron alloy interface region (for example, an iron rich alloy (CoFeof CoFeX where X may be nickel and/or one or more non-magnetic materialssuch as one or more transition metals or boron)) within the referencelayer which is adjacent to and/or in contact with the dielectric layer.In one embodiment, the high-iron alloy interface region is greater thanor equal to 50% iron by atomic percentage).

With reference to FIGS. 1A, 1B, 2A and 2B, one or more dielectric layersmay then be deposited on the fixed magnetic region using any techniquenow known or later developed. The one or more dielectric layers may be,for example, a magnesium-oxide or an aluminum-oxide. The one or moredielectric layers may provide the tunnel barrier region of themagnetoresistive stack/structure. In one embodiment, the one or moredielectric layers are fabricated or provided using the materials andprocesses described and illustrated in U.S. Pat. Nos. 8,686,484 and9,136,464.

With continued reference to FIGS. 1A, 1B, 2A and 2B, a free magneticregion is then deposited on the one or more dielectric layers. Here, thefree magnetic region may include a plurality of ferromagnetic materiallayers (for example, one or more of cobalt, iron, and nickel) as well asone or more non-magnetic material layers (for example, ruthenium,tantalum, aluminum). (See, for example, U.S. Pat. 8,686,484). The freemagnetic region may include ferromagnetic interface regions. (See, forexample, FIG. 4A). In one embodiment, the ferromagnetic interfaceregions include at least 50% iron by atomic percentage (hereinafter“high-iron interface regions”). (See, for example, U.S. Pat. No.8,686,484). Notably, the high-iron interface regions may include acontinuous layer of iron (for example, pure iron), a discontinuous layerof iron, and/or an interfacial layer of high-iron alloy (wherein thealloy includes greater than or equal to 50% iron by atomic percentage).In one embodiment, the high-iron interface region provides at least anatomic layer of material at the surface of the free magnetic regionhaving mainly iron atoms. Notably, the high-iron interface regions mayprovide, among other things, high perpendicular interface anisotropyenergy.

After deposition of the materials/layers of the free magnetic region, inone embodiment, a spacer region is deposited followed by anelectrode/via/line. (See, FIG. 1A). In another embodiment, one or moresecond dielectric layers are deposited followed by a spacer region andan electrically conductive material (for example, a metal of anelectrode/via/line). (See, FIG. 1B). The spacer region may be anon-magnetic region that provides a barrier between the free magneticregion and the electrically conductive material of theelectrode/via/line. (See, for example, U.S. Pat. No. 8,686,484). Indeed,the one or more second dielectric layers of the embodiment of FIG. 1B,may provide, among other things, an additional barrier between the freemagnetic region and the electrically conductive material of, forexample, the electrode/via/line.

Notably, the magnetoresistive stack/structure may be fabricated from thelayers and/or regions of FIGS. 1A and 1B using any process technique nowknown or later developed, for example, using well known conventionaldeposition and lithographic techniques to form the magnetoresistivestack/structure from the layers and/or regions of FIGS. 1A and 1B. Inone embodiment, the present inventions employ the process techniquesdescribed and/or illustrated in Provisional Patent Application Nos.62/111,976 and 62/249,196, which are incorporated herein by reference intheir entirety; notably, all of the inventions/embodiments describedand/or illustrated herein may be implemented or employed in conjunctionwith the inventions/embodiments of the '976 and '196 applications.

During processing, the magnetoresistive stack/structure including theseed region of the present inventions maintains or includes,notwithstanding subsequent or additional processing (for example,annealing processes having temperatures of 400° C.), improved properties(for example, magnetoresistance (MR) and resistance-area product (RA) ofthe stack/structure). For example, a MTJ stacks/structure, having aperpendicular magnetic anisotropy, maintains or includes improvedproperties or characteristics (for example, magnetoresistance (MR) andresistance-area product (RA) of the stack/structure) after processing(for example, one or more annealing processes after deposition/formationof the magnetic region). Indeed, a magnetoresistive stack/structureincluding such a seed region may be more reliable and thermally stable(relative to conventional seed regions) and/or provide greater thermalendurance notwithstanding subsequent or additional processing (forexample, annealing processes having temperatures of 400° C.).

There are many inventions described and illustrated herein. Whilecertain embodiments, features, attributes and advantages of theinventions have been described and illustrated, it should be understoodthat many others, as well as different and/or similar embodiments,features, attributes and advantages of the present inventions, areapparent from the description and illustrations. As such, the aboveembodiments of the inventions are merely exemplary. They are notintended to be exhaustive or to limit the inventions to the preciseforms, techniques, materials and/or configurations disclosed. Manymodifications and variations are possible in light of this disclosure.It is to be understood that other embodiments may be utilized andoperational changes may be made without departing from the scope of thepresent inventions. As such, the scope of the inventions is not limitedsolely to the description above because the description of the aboveembodiments has been presented for the purposes of illustration anddescription.

Indeed, the present inventions are neither limited to any single aspectnor embodiment thereof, nor to any combinations and/or permutations ofsuch aspects and/or embodiments. Moreover, each of the aspects of thepresent inventions, and/or embodiments thereof, may be employed alone orin combination with one or more of the other aspects of the presentinventions and/or embodiments thereof.

Many modifications, variations, combinations and/or permutations arepossible in light of the above teaching. For example, although certainexemplary techniques are described and/or illustrated above in thecontext of MTJ-based magnetoresistive stacks/structures, as noted above,the present inventions may be implemented in GMR-based magnetoresistivestacks/structures (for example, sensor and memory). For the sake ofbrevity such discussions/illustrations will not be repeated in thecontext of GMR-based magnetoresistive stacks/structures having seedregion of the present inventions—but it is to be interpreted as entirelyapplicable to GMR-based stacks/structures where a conductor (rather thana dielectric material in the case of MTJ-based stacks/structures) isdisposed between magnetic materials.

Further, in one exemplary embodiment, the free magnetic region includesa plurality of ferromagnetic materials and/or layers (for example,including materials such as cobalt, iron, boron, nickel and/or one ormore alloys thereof such as a cobalt-iron alloy or a cobalt-iron-boronalloy) but does not include a plurality of insertion layers in analternating ferromagnetic layer -insertion layer structure. (See, FIG.4B). Albeit, in another embodiment, one or more insertion layers areincluded and not omitted from the free magnetic region. Moreover, thefree magnetic region may omit one or both of the ferromagnetic interfaceregions (for example, for example, iron or an iron alloy) whichinterface with and/or contact the dielectric layer (i.e., tunnel barrierof the magnetoresistive stack/structure) and the spacer region (see FIG.1A) or the first and second dielectric layers (see FIG. 1B).

Some embodiments of MTJ stacks/structures may have layers with aspecified level of purity. As noted above, in one aspect, the describedembodiments relate to, among other things, methods of manufacturingmagnetoresistive devices, such as, e.g., one or more MTJ stacks. As willbe described in greater detail below, embodiments of the presentdisclosure relate to the formation of seed regions including an alloyincluding nickel (Ni) and chromium (Cr) (e.g., a nickel-chromium (NiCr)alloy) to allow for the formation of a SAF within a suitablemagnetoresistive stack/structure. In some embodiments, the alloyincluding nickel (Ni) and chromium (Cr) may be of high purity (e.g., 99atomic percent (at. %) or greater of the alloy is nickel (Ni) and/orchromium (Cr)).

In one or more embodiments, the seed region is implemented in anMTJ-type magnetoresistive stack having a perpendicular magneticanisotropy wherein a magnetic region (e.g., a SAF) is disposed on or inphysical contact with the seed region. SAFs may break down or becomeless effective when exposed to high temperatures. SAFs exposed to hightemperatures may lose their in-plane or out-of-plane magneticanisotropy. When SAFs are integrated into magnetoresistive stacks,subsequent processing steps may expose the SAFs to high temperatures anddamage or otherwise negatively affect the performance of the SAF (e.g.,worsened magnetoresistance (MR) and/or resistance-area product (RA)). Insome embodiments, the stack including seed regions described belowmaintains or includes improved MR and/or RA. A magnetoresistive stackincluding a seed region as described herein may exhibit improvedreliability, thermal stability, and/or thermal endurance. In one or moreembodiments, the seed regions described herein may facilitate growththereon of one or more magnetic layers of a “fixed” region (e.g., one ormore layers of a SAF). Magnetic layers formed above a seed region, asdescribed herein, may be more uniform or include sharper interfacesrelative to stacks formed in the absence of such seed regions.

Referring now to FIG. 5A, an exemplary magnetoresistive stack 100 isshown, including a “fixed” magnetic region 140 and a “free” magneticregion 160 disposed between a first electrode 110 (e.g., a via or otherconductor) and a second electrode 120 (e.g., a via or other conductor).A seed region 130 may be disposed between the first electrode 110 andthe “fixed” region 140. Magnetoresistive stack 100 may include anintermediate layer 150 (e.g., of a dielectric material) disposed betweenthe “fixed” region 140 and the “free” region 160, and a spacer region170 between the “free” region 160 and the second electrode 120.

Referring to FIG. 5B, another exemplary magnetoresistive stack 100′ isshown, including a “fixed” magnetic region 140 and a “free” magneticregion 160 disposed between a first electrode 110 (e.g., a via or otherconductor) and a second electrode 120 (e.g., a via or other conductor).A seed region 130 may be disposed between the first electrode and afirst “fixed” region 140. Magnetoresistive stack 100′ may include afirst intermediate layer 150 (e.g., made of a dielectric material)disposed between the first “fixed” region 140 and the “free” region 160and a second intermediate layer 150′ (e.g., also made of a dielectricmaterial) above the “free” region 160. In some embodiments, a second“fixed” region 180 may be disposed above the second intermediate layer150′. Such embodiments may be referred to more commonly as a dual spinfilter (DSF) magnetoresistive stack/structure. In some embodiments, themagnetoresistive stack 100′ may optionally include a spacer region (notpictured in FIG. 5B) between the second “fixed” region 180 and thesecond electrode 120.

Various seed regions 130 and methods of forming seed regions 130 andother layers of exemplary magnetoresistive stacks 100, 100′ will now bedescribed. Although various embodiments will be discussed, it should beunderstood that aspects of one embodiment may be combined with aspectsof another embodiment without departing from the intended scope of thepresent disclosure. Referring to FIGS. 6A-6F, various exemplary seedregions 130 are shown disposed between the first electrode 110 and“fixed” region 140. Although the remainder of the magnetoresistive stack100, 100′ is not shown in FIGS. 6A-6F, it should be understood that theseed regions 130 described may be incorporated into any suitablemagnetoresistive stack 100, 100′ now known or later developed.

As shown in FIG. 6A, a seed region 130 may be formed directly on orabove top a first electrode 110. The seed region 130 may act as asurface on which one or more layers of a “fixed” region 140 may beformed (e.g., directly or indirectly) and allows current to passbidirectionally from the first electrode 110 to the “fixed” region 140.The seed region 130 may include one or more of nickel (Ni), chromium(Cr), cobalt (Co), iron (Fe), or alloys thereof. In some embodiments,the seed region 130 may include an alloy including nickel (Ni) andchromium (Cr), such as, e.g., a NiCr alloy. The seed region 130 mayfurther include one or more other metals or metal alloys, such as, byway of non-limiting example, palladium (Pd), platinum (Pt), nickel (Ni),tantalum (Ta), ruthenium (Ru), tungsten (W), molybdenum (Mo), iron-boron(FeB), cobalt-iron-boron (CFeB), tantalum-nitride (TaN), or combinationsthereof. In some embodiments, the entire seed region 130 may comprise analloy including nickel (Ni) and chromium (Cr) (e.g., NiCr alloy) thatmakes up 99% or greater atomic composition of the seed region. Theremaining 1% or less may be considered impurities. Stated differently,for a given thickness or volume of seed region 130, the entire thicknessor volume may have a composition that includes an atomic compositionwith 99% or greater of an alloy including nickel (Ni) and chromium (Cr)(e.g., NiCr alloy). In further embodiments, an alloy including nickel(Ni) and chromium (Cr) (e.g., NiCr alloy) makes up greater than or equalto 99.9 at. % composition of the seed region 130, greater than or equalto 99.99 at. % of the seed region 130, greater than or equal to 99.999,99 at. % to 99.999 at. % of the seed region 130, or 99.9 at. % to 99.99at. % of the seed region 130. The alloy including nickel (Ni) andchromium (Cr) of seed region 130 may include a chromium content greaterthan or equal to approximately 25 at. % chromium, greater than or equalto approximately 30 at. % chromium, greater than or equal toapproximately 40 at. % chromium, greater than or equal to approximately50 at. % chromium, greater than or equal to approximately 60 at. %chromium, approximately 25 at. % to 50 at. % chromium, or approximately30 at. % to 45 at. % chromium. In one or more embodiments, the chromiumcontent of the alloy including nickel (Ni) and chromium (Cr) of seedregion 130 may be sufficient so as to cause seed region 130 to benon-magnetic.

Seed region 130 may be formed by any physical vapor deposition (PVD) orchemical vapor deposition technique (CVD) known in the art (e.g.,sputtering, magnetron sputtering, ion beam deposition, atomic layerdeposition, evaporative techniques). In some embodiments, the NiCr alloyof seed region 130 may be formed by depositing alternating layers ofnickel (Ni) and chromium (Cr). Each layer of nickel (Ni) may include 99at. % to 99.999 at. % or 99.9 at. % to 99.99 at. % nickel (Ni). Eachlayer of chromium (Cr) may include 99 at. % to 99.999 at. % or 99.9% to99.99 at. % chromium (Cr).

In one or more embodiments, seed region 130 may have a thickness greaterthan or equal to approximately 20 angstroms (Å), greater than or equalto approximately 30 Å, greater than or equal to approximately 40 Å,greater than or equal to approximately 50 Å, greater than or equal toapproximately 60 Å, greater than or equal to approximately 70 Å, greaterthan or equal to approximately 80 Å, approximately 25 Å to 100 Å,approximately 30 Å to 75 Å, approximately 30 Å to 60 Å, or approximately35 Å to 50 Å.

In one or more embodiments, the seed region 130 may include one or moreNiCr alloy layers 135 and one or more auxiliary layers 131. In someembodiments, such as, for example the ones shown in FIGS. 6B, 6D, a seedregion 130 may be formed such that an auxiliary layer 131 is above andin contact with the first electrode 110 and a layer 135 (of e.g., a NiCralloy) is below and in contact with the “fixed” region 140.

In other embodiments, such as the one shown in FIG. 6C, a seed region130 may be configured such that an alloy (e.g., an alloy includingnickel and chromium) layer 135 is above and in contact with the firstelectrode 110 and an auxiliary layer 131′ is below and in contact withthe “fixed” region 140. In some embodiments, a seed region 130 mayinclude a plurality of auxiliary layers 131 and/or a plurality of alloylayers 135, as shown in FIGS. 6C-6E. A seed region 130 may include equalnumbers of auxiliary layers 131 and alloy layers 135, for example, asshown in FIG. 6D. In other embodiments, such as the one shown in FIG.6E, a seed region 130 includes more alloy layers 135 than auxiliarylayers 131. In still other embodiments, a seed region 130 includes moreauxiliary layers 131 than alloy layers 135.

An alloy layer 135 may include one or more of nickel (Ni), chromium(Cr), cobalt (Co), iron (Fe), or alloys thereof. In some embodiments, analloy layer may include a NiCr alloy. The NiCr alloy layer 135 mayfurther include one or more other metal or metal alloy dopants, such as,by way of non-limiting example, palladium (Pd), platinum (Pt), nickel(Ni), tantalum (Ta), ruthenium (Ru), tungsten (W), molybdenum (Mo), FeB,CFeB, TaN, or combinations thereof. In some embodiments, the alloy layer135 may include greater than or equal to 99 atomic percent (at. %) NiCralloy, based on the total composition of the region. In furtherembodiments, alloy layer 135 may include greater than or equal to 99.9at. % NiCr alloy, greater than or equal to 99.99 at. % NiCr alloy,greater than or equal to 99.999 at. % NiCr alloy, approximately 99 at. %to approximately 99.999 at. %, or approximately 99.9 at. % toapproximately 99.99 at. %. The NiCr alloy may include a chromium (Cr)content greater than or equal to 25 at. % chromium, greater than orequal to 30 at. % chromium, greater than or equal to 40 at. % chromium,greater than or equal to 50 at. % chromium, greater than or equal to 60at. % chromium, approximately 25 at. % to approximately 50 at. %chromium, or approximately 30 at. % to approximately 45 at. % chromium.

Alloy layer 135 may have a thickness greater than or equal toapproximately 10 Å, greater than or equal to approximately 15 Å, greaterthan or equal to approximately 20 Å, greater than or equal toapproximately 25 Å, greater than or equal to approximately 30 Å, greaterthan or equal to approximately 35 Å, greater than or equal toapproximately 40 Å, approximately 10 Å to approximately 50 Å,approximately 15 Å to approximately 40 Å, approximately 15 521 toapproximately 30 Å, or approximately 20 Å to approximately 25 Å.

The one or more auxiliary layers 131 may include one or more of iron(Fe), cobalt (Co), palladium (Pd), platinum (Pt), nickel (Ni), tantalum(Ta), ruthenium (Ru), tungsten (W), molybdenum (Mo), FeB, TaN, CFeB, orcombinations thereof. In embodiments where an auxiliary layer 131 is incontact with a first electrode 110, the composition of the auxiliarylayer 131 may be chosen to be compatible with the first electrode 110(e.g., made out of the same or similar metals or alloys). In otherembodiments, the composition of auxiliary layer 131 may be differentthan the composition of the first electrode 110 it is in contact with.Similarly, in embodiments where an auxiliary layer 131 is in contactwith one or more layers of the “fixed” region 140, the composition ofauxiliary layer 131 may be chosen to be the same or similar metal ormetal alloys as the one or more layers of the “fixed” region 140 it isin contact with. In other embodiments, the composition of auxiliarylayer 131 may be different than the composition of the one or morelayers of the “fixed” region 140 it is in contact with. In embodimentswhere a seed region 130 comprises a plurality of auxiliary layers 131,each auxiliary layer 131 may have the same or similar composition. Inother embodiments where a seed region 130 comprises a plurality ofauxiliary layers 131, at least one auxiliary layer 131 may have adifferent composition than the other auxiliary layers 131.

Referring to FIG. 6E, one exemplary seed region 130 may include twoalloy layers 135, 135′ and an auxiliary layer 131 disposed therebetween.One alloy layer 135 is formed on the first electrode 110, an auxiliarylayer 131 is formed on the alloy layer 135, then another alloy layer135′ may be formed on the auxiliary layer 131, allowing for one or morelayers of the “fixed” region 140 to be formed on the top alloy layer135′ of seed region 130. In each instance, alloy layers 135 and 135′ mayinclude an alloy including nickel and chromium. In this way, both thefirst electrode 110 and the “fixed” region 140 are in contact with analloy layer 135, 135′ of seed region 130.

Any of the embodiments described herein may also include a dusting layer139 deposited above seed region 130, as is shown in FIG. 6F. Forexample, if a NiCr seed region 130 is used, dusting layer 139 may bedeposited over the NiCr seed region 130, and cobalt and/or platinumlayers of “fixed” region 140 may be deposited on top of dusting layer139. In some embodiments, when a “fixed” region 140 having layers ofcobalt (Co) and/or platinum (Pt) is used, a strong crystal texture maybe desirable in order to obtain a strong perpendicular magneticanisotropy and/or a larger exchange coupling between AP1 and AP2. Strongcrystal texture of “fixed” region 140 under intermediate layer 150 maylead to a rough intermediate layer 150, reducing the MTJ stack/structuretime-dependent dielectric breakdown, and thus improving MRAM endurance.The inclusion of dusting layer 139 between seed region 130 and “fixed”region 140 may affect the crystalline structure of layers formed abovedusting layer 139, e.g., “fixed” region 140 and/or intermediate layer150 (e.g., a dielectric layer, an oxide layer, MgO). For example, one ormore regions formed above dusting layer 139 may be formed with astronger crystal texture as compared to magnetoresistive structures notincluding a dusting layer 139. The formation of a dusting layer 139beneath one or more SAF or SyF structures may increase the ferromagneticor antiferromagnetic coupling of the SAF and/or SyF, and this effect maybe more pronounced in SAFs or SyFs including a ruthenium (Ru) couplinglayer. Further, the inclusion of dusting layer 139 between seed region130 and “fixed” region 140 may reduce wear and/or increase thedurability of intermediate layer 150, for the reasons described above.

In embodiments in which the multilayer SAF (or SyF) of the “fixed”magnetic region 140 includes cobalt (Co) and platinum (Pt), an initiallayer of ferromagnetic material including cobalt (Co) may be depositedon seed region 130 or dusting layer 139. In embodiments where themultilayer SAF includes cobalt (Co) and nickel (Ni), an initial layer offerromagnetic material including nickel (Ni) may be deposited on seedregion 130 or dusting layer 139.

Dusting layer 139 may include molybdenum (Mo), magnesium (Mg), iron(Fe), platinum (Pt), ruthenium (Ru), or combinations and alloys thereof(e.g., iron-boron (FeB), cobalt-iron (CoFe), cobalt-iron-boron (CoFeB)).In some embodiments, dusting layer 139 may have a thickness of less than12 Å, greater than approximately 2 Å, approximately 1 Å to approximately12 Å, approximately 2 Å to approximately 10 Å, approximately 2 Å toapproximately 8 Å, approximately 2 Å to approximately 6 Å, approximately4 A to approximately 10 Å, or approximately 6 Å to approximately 10 Å.

In some embodiments, the AP1 and AP2 switching fields may vary based onthe thickness and/or material of dusting layer 139. For example, similarexchange coupling fields may be obtained with a dusting layer 139 formedof iron (Fe), platinum (Pt), ruthenium (Ru), molybdenum (Mo), and/orcobalt-iron (CoFe), while dusting layers 139 formed of magnesium (Mg)and/or cobalt-iron-boron (CoFeB) may lead to more of a reduction inexchange coupling. Exemplary embodiments of the present disclosure mayinclude a NiCr₆₀ seed region 130 with no dusting layer 139, a NiCr₆₀seed region 130 with a Mg₅ dusting layer 139 on top, a NiCr₆₀ seedregion 130 with a Fe₅ dusting layer 139 on top, a NiCr₆₀ seed region 130with a Pt₅ dusting layer 139 on top, a NiCr₆₀ seed region 130 with a Ru₄dusting layer 139 on top, a NiCr₆₀ seed region 130 with a Ru₉ dustinglayer 139 on top, a NiCr₆₀ seed region 130 with a Mo₅ dusting layer 139on top, a NiCr₆₀ seed region 130 with a Mo₁₀ dusting layer 139 on top, aNiCr₆₀ seed region 130 with a CoFe₅ dusting layer 139 on top, and/or aNiCr₆₀ seed region 130 with a CFB₂O₅ dusting layer 139 on top.

In one or more embodiments, “fixed” region 140 may be a fixed, unpinnedSAF multilayer structure disposed on seed region 130. The fixed,unpinned SAF multilayer structure may include at least two magneticregions (e.g., made of one or more layers) separated by a couplingregion. The one or more magnetic regions may include nickel (Ni), iron(Fe), and cobalt (Co), palladium (Pd), platinum (Pt), chromium (Cr),manganese (Mn), magnesium (Mg), and alloys or combinations thereof. Thecoupling region may be an antiferromagnetic coupling region thatincludes non-ferromagnetic materials such as, for example, iridium (Ir),ruthenium (Ru), rhenium (Re), or rhodium (Rh). In some embodiments, oneor more magnetic regions may comprise a magnetic multilayer structurethat includes a plurality of layers of a first ferromagnetic material(e.g., cobalt (Co)), a second ferromagnetic material (e.g., nickel(Ni)), and/or a paramagnetic material (e.g., platinum (Pt)).

Additionally, or in the alternative, in some embodiments, the “fixed”region 20 may include one or more synthetic ferromagnetic structures(SyF). Since SyFs are known to those skilled in the art, they are notdescribed in greater detail herein. In some embodiments, the “fixed”region 140 may have a thickness of approximately 8 Å to approximately300 Å, approximately 15 Å to approximately 110 Å, greater than or equalto 8 Å, greater than or equal to 15 Å, less than or equal to 300 Å, orless than or equal to 110 Å.

In some embodiments, the “fixed” region 140 may also include one or moreadditional layers, such as for example, a transition region and/or areference region. The transition region and/or reference region may bedisposed at the top of the “fixed” region, proximate to an overlyinglayer (e.g., an intermediate layer, described below). The referenceand/or transition regions may include one or more layers of materialthat, among other things, facilitate and improve the growth of one ormore overlying regions during manufacture of a magnetoresistive stack.The reference region may include cobalt (Co), iron (Fe), and boron (B),CoFeB, CoFeBTa, CoFeTa, or combinations thereof. The transition regionmay include non-ferromagnetic transition metals such as, for example,tantalum (Ta), titanium (Ti), tungsten (W), ruthenium (Ru), niobium(Nb), zirconium (Zr), and/or molybdenum (Mo).

“Fixed” region 140 may be deposited using any technique now know orlater developed. In some embodiments, one or more of the magneticregions of the “fixed” region 140 may be deposited using a “heavy” inertgas (e.g., xenon (Xe), argon (Ar), krypton (Kr)), at room temperature,approximately 25° C., approximately 15° C. to approximately 40° C.,approximately 20° C. to approximately 30° C. In some embodiments, thecoupling region of the SAF may also be deposited using a “heavy” inertgas at similar temperatures.

The various regions or layers of “fixed” region 140 may be depositedindividually during manufacture. However, as would be recognized bythose of ordinary skill in the art, the materials that make up thevarious regions may alloy with (intermix with and/or diffuse into) thematerials of adjacent regions during subsequent processing (e.g.,deposition of overlying layers, high temperature or reactive etchingtechnique, and/or annealing). Therefore, a person skilled in the artwould recognize that, although the different regions of “fixed” region140 may appear as separate regions with distinct interfaces immediatelyafter formation of these regions, after subsequent processingoperations, the materials of the different layers or regions may alloytogether to form a single alloyed “fixed” region 140 having a higherconcentration of different materials at interfaces between differentregions. Thus, in some cases, it may be difficult to distinguish thedifferent regions of the “fixed” region 140 in a finishedmagnetoresistive stack.

Referring now to FIG. 7, a “fixed” region 140 may include a SAF and beformed above and/or in contact with seed region 130. A first magneticregion 142 may be formed on seed region 130. The magnetic region 142 maycomprise one or more layers of magnetic or ferromagnetic material. Insome embodiments, each layer of magnetic or ferromagnetic material has athickness less than or equal to approximately 10 Å, less than or equalto approximately 8 Å, less than or equal to approximately 6 Å, less thanor equal to approximately 5 Å, less than or equal to approximately 4 Å,less than or equal to approximately 3 Å, or approximately 1 Å toapproximately 6 Å. The one or more layers of magnetic layer 142 may beformed by any physical vapor deposition (PVD) or chemical vapordeposition (CVD) technique known in the art (e.g., sputtering, magnetronsputtering, ion beam deposition, atomic layer deposition, evaporativetechniques).

In some embodiments, the first magnetic region 142 formed on seed region130 comprises cobalt (Co) and nickel (Ni) and a layer of cobalt may bedeposited directly on seed region 130. In other embodiments, a layer ofnickel (Ni) may be deposited directly on seed region 130.

After the first magnetic region 142 is formed, a coupling layer 145 maybe formed above and/or in contact with the first magnetic region 142.The coupling layer 145 may be formed by any physical vapor deposition(PVD) or chemical vapor deposition (CVD) technique known in the art(e.g., sputtering, magnetron sputtering, ion beam deposition, atomiclayer deposition, evaporative techniques). In some embodiments, firstmagnetic region 142 may include a layer of cobalt (Co) in contact withcoupling layer 145. A second magnetic region 142′ may be formed oncoupling layer 145. The second magnetic region 142′ may have the samecomposition as the first magnetic region 142, or the second magneticregion 142′ may have a different composition than the first magneticregion 142. In some embodiments, a layer of cobalt (Co) is formed on thecoupling layer 145 as part of the second magnetic region 142′. Thecoupling layer 145 may be disposed between two cobalt (Co) layers, oneof the first magnetic region 142 and other of the second magnetic region142′.

In some embodiments, “fixed” region 140 may include a SAF whichpossesses perpendicular magnetic anisotropy. In one or more embodiments,the seed region 130 facilitates the growth of smoother layers of the SAFwhich have sharper interfaces. Seed regions 130 described herein mayfacilitate growth, deposition, or formation of the SAF and may alsoprovide less stress thereby assisting in the maintenance of high MR attemperatures greater than or equal to approximately 400° C., greaterthan or equal to approximately 450° C., or greater than or equal toapproximately 500° C. The thermal durability of the SAF formed on seedregions 130 described herein may allow for the SAF to maintain itsmagnetic properties during later processing of the magnetoresistivestack or MRAM device.

Still referring to FIG. 7, after a “fixed” region 140 is formed, one ormore intermediate layers 150 (e.g., made of a dielectric material) maythen be formed above and/or in contact with the “fixed” magnetic region140, as previously described. The one or more dielectric layers 150 mayinclude metal oxides (e.g., MgO or Al_(x)O_(x)) and may provide thetunnel barrier for the magnetoresistive stack.

Similarly, a “free” magnetic region 160 may be formed above and/or incontact with the one or more intermediate layers 150. The “free”magnetic region 160 may include one or more ferromagnetic layers (e.g.,layers including cobalt (Co), iron (Fe), nickel (Ni)). In someembodiments, the free magnetic region also may include one or moreadditional materials such as, e.g., boron (B). In some embodiments,“free” magnetic region 160 may include one or more non-magnetic layers(e.g., ruthenium (Ru), tantalum (Ta), aluminum (Al)). “Free” magneticregion 160 may also include high-iron interface layers (e.g., layerswhich contain greater than or equal to 50 at. % iron).

In another example, “free” magnetic region 160 may comprise at last twoferromagnetic regions separated by a coupling region (e.g., includingtantalum (Ta), tungsten (W), molybdenum (Mo), ruthenium (Ru), rhodium(Ro), rhenium (Re), iridium (Ir), chromium (Cr), osmium (Os), and theircombinations). The coupling region may provide either ferromagneticcoupling or antiferromagnetic coupling between the ferromagneticlayers/regions of the “free” magnetic region 160. Notwithstanding thespecific construction of “free” magnetic region 160, “free” magneticregion 160 may include a magnetic vector (or moment) that can be movedor switched by applied magnetic fields or spin torque currents. “Free”magnetic region 160 may be formed from any ferromagnetic material havingtwo or more stable magnetic states. These materials may include alloysof one or more of the ferromagnetic elements nickel (Ni), iron (Fe),cobalt (Co), and boron (B). Additional elements may be added to thealloys to provide improved magnetic, electrical, or microstructuralproperties. In some embodiments, similar to “fixed” region 20, “free”region 60 also may include one or more SAF or SyF structures. Ingeneral, “free” region 60 may have any thickness, such as, for example,approximately 7-40 Å, preferably approximately 20-30 Å, and morepreferably approximately 25-28.5 Å.

It should be noted that while not specifically described, variouslithographic, etching processes, or finishing steps common in the art(e.g., ion beam etching, chemical etching, chemical-physicalplanarization) may be performed after the formation of one or morelayers of the exemplary magnetoresistive stacks. Exemplary methods forforming a magnetoresistive stack 100, 100′ according to embodiments ofthe present disclosure will now be discussed, reference to parts and thenumbered labels shown in FIGS. 5A-7 may be used.

FIG. 8 is a flow chart of a method 400 of manufacturing amagnetoresistive stack, e.g., magnetoresistive stack 100, according tothe present disclosure. A first electrically conductive material 110(e.g., an electrode, via, and/or conductor) may be formed above asubstrate, such as, for example, a silicon-based substrate (step 410). Aseed region 130 may then be formed above the first electricallyconductive material 110 (step 420). The seed region 130 may include anyof the aforementioned described seed regions 130. Next, a “fixed”magnetic region 140 (e.g., a SAF) may be formed above the seed region130 (step 430). Subsequently, a intermediate layer 150 (e.g., adielectric layer) may be formed above the “fixed” magnetic region 140(step 440). Next, a “free” magnetic region 160 may be formed over theintermediate layer 150 (step 450). After the “free” magnetic region 160is formed, an optional spacer region may be formed above the “free”magnetic region 160 in some embodiments. A second electricallyconductive material 120 (e.g., an electrode, via, and/or conductor) maybe next (step 470), thereby providing electrical connectivity tomagnetoresistive stack 100.

FIG. 9 is a flow chart of another method 500 of manufacturing amagnetoresistive stack 100, according to the present disclosure. A firstelectrically conductive material 110 (e.g., an electrode, via, and/orconductor) may be formed above a substrate, such as, for example, asilicon-based substrate (step 510). A seed region 130 may then be formedabove the first electrically conductive material 110 (step 520). Theseed region 130 may include any of the aforementioned described seedregions 130. Next, a “fixed” magnetic region 140 (e.g., a SAF) may beformed above the seed region 130 (step 530). Subsequently, a firstintermediate layer 150 (e.g., a dielectric layer) may be formed abovethe “fixed” magnetic region 140 (step 540). Next, a “free” magneticregion 160 may be formed over the first intermediate layer 150 (step550). After the “free” magnetic region 160 is formed, a secondintermediate layer 150′ (e.g., a dielectric layer) may be formed abovethe “free” magnetic region 160 (step 560). A second “fixed” magneticregion 180 may then be formed above the second intermediate layer 150′(step 570). Then, in some embodiments, an optional spacer region 170 maybe formed above the second “fixed” region 180. A second electricallyconductive material 120 (e.g., an electrode, via, and/or conductor) maybe next formed (step 580), thereby providing electrical connectivity tomagnetoresistive stack 100′.

As alluded to above, the magnetoresistive devices of the presentdisclosure, including seed regions 130 described herein, may beimplemented in a sensor architecture or a memory architecture (amongother architectures). For example, in a memory configuration, themagnetoresistive devices, including embodiment magnetoresistivestacks/structures described herein, may be electrically connected to anaccess transistor and configured to couple or connect to variousconductors, which may carry one or more control signals, as shown inFIG. 10. The magnetoresistive devices of the current disclosure may beused in any suitable application, including, e.g., in a memoryconfiguration. In such instances, the magnetoresistive devices may beformed as an integrated circuit comprising a discrete memory device(e.g., as shown in FIG. 11) or an embedded memory device having a logictherein (e.g., as shown in FIG. 12), each including MRAM, which, in oneembodiment is representative of one or more arrays of MRAM having aplurality of magnetoresistive stacks, according to certain aspects ofcertain embodiments disclosed herein. In one embodiment, a plurality ofmagnetoresistive memory stacks/structures may be fabricated and/orincorporated on an integrated circuit, for example, in an MRAM array.(See, FIGS. 11 and 12).

The alloys described and illustrated herein may be formed using anytechnique now known or later developed. For example, the alloys may beformed via co-deposition (for example, via sputtering and/or evaporatingof a nickel-chrome alloy or via concurrently and separately sputteringand/or evaporating nickel and chromium). In addition thereto, or in lieuthereof, sequentially depositing materials, together with one or moreannealing processes, may be employed to form the alloys. Again, anytechnique now known or later developed may be used to form the alloysdescribed and illustrated herein.

The fixed, unpinned SAF region may include two multi-layer structures(AP1 and AP2—for example, like that of the magnetic multi-layerstructure of FIG. 3A). In another embodiment, the fixed, unpinned SAFregion may include only one multi-layer structure (either AP2 or AP1)and a non-multi-layer structure (the other of AP2 or AP1). Here, themagnetic multi-layer structure and a non-multi-layer structure areantiferromagnetically coupled via a coupling layer. The multi-layerstructure (AP1 or AP2) may include any particular structure orarchitecture (and be manufactured) consistent with any of the embodimentdescribed and/or illustrated herein.

Further, as mentioned above, in one embodiment, the fixed magneticregion includes multi-layer structures (AP1 or AP2) and a transitionlayer and reference layer disposed between AP2 and the dielectric layer.(See, FIG. 3C). Here, the transition layer may include one or morelayers of material that facilitate/improve growth of the dielectriclayer (which is a tunnel barrier in the MTJ structure) duringfabrication. In one embodiment, the reference layer may include one ormore or all of cobalt, iron, boron and tantalum (for example, in analloy—such as an amorphous alloy (e.g., CoFeB or CoFeBTa or CoFeTa) andthe transition layer may include a non-ferromagnetic transition metalsuch as tantalum, titanium, tungsten and/or molybdenum. Moreover, inanother embodiment, the reference layer may include a layer of iron (forexample, deposited as pure or substantially pure iron) and a layer of(i) cobalt and iron or (ii) cobalt, iron and boron (for example,deposited as an alloy) wherein, after further/final processing (e.g.,after annealing), the layer of iron at the interface may form acontinuous atomic layer or may mix with the underlying ferromagneticalloy in the final annealed structure, resulting in a high-iron alloyinterface region (for example, greater than or equal to 50% iron byatomic percentage) within the reference layer which is adjacent to thedielectric layer.

Notably, while the magnetic materials layer(s) and magnetic materials ofthe MTJ stack/structure are illustrated as a single layer, the magneticmaterials layer(s) and magnetic materials may include a number ofdifferent layers of both magnetic and nonmagnetic material. For example,the layers may include multiple layers of magnetic material, dielectriclayers that provide, for example, one or more diffusion barriers,coupling layers between layers of magnetic material that provide forferromagnetic or antiferromagnetic coupling, antiferromagnetic material.For example, one of the magnetic material layer(s) may include a set oflayers forming a SAF and a layer of antiferromagnetic material, seedinglayers, diffusion layers as well as non-contiguous layers of magneticand nonmagnetic material. The other magnetic material layer(s) mayinclude a set of layers corresponding to a SyF, seeding layers, spacinglayers, diffusion layers as well as non-contiguous layers of magneticand nonmagnetic material. Notably, each of the layers shown to beincluded in the magnetoresistive device may be a composite layer thatincludes multiple sub-layers. Other embodiments may include multipleSAFs, SyFs, and tunnel barriers in addition to the other layers, wherethe materials and structures are arranged in various combinations andpermutations now known or later developed.

For example, one or more regions (for example, the fixed magneticregion) of the magnetoresistive stack/structure (for example, amagnetoresistive memory stack/structure or a magnetoresistivesensor/transducer stack/structure) may include and/or consist of a SyF.For example, the fixed magnetic region may be a pinned or unpinned SyFincluding, for example, a multi-layer SyF a plurality of layers of oneor more magnetic or ferromagnetic materials separated by anferromagnetic coupling layer (for example, an coupling layer includingruthenium or rhodium having a thickness that provides ferromagneticcoupling). Such a SyF may be deposited or formed on the seed region.Notably, all of the inventions described and/or illustrated herein maybe implemented in conjunction with a pinned or unpinned SyF embodiment;however, for the sake of brevity, such combinations and permutationswill not be described/illustrated separately herein.

Further, the one or more layers of magnetic materials (for example,nickel, iron, cobalt, and alloys thereof) may be etched, formed and/orpatterned using any etchants and/or technique now known or laterdeveloped—for example, using mechanical and/or chemical techniques (forexample, an ion beam etching, low bias power sputter technique or achemical etch technique (such as a conventional fluorine and/or chlorinebased etch technique)). Where the magnetic material stack includes oneor more SAFs or SyFs, the one or more layers of magnetic materialslayers may also include one or more non-magnetic materials layers (forexample, copper, aluminum or non-ferromagnetic transition metals, suchas tantalum, niobium, vanadium, zirconium, molybdenum or ruthenium).Notably, one or more magnetic material stack may include SAF and SyFstructures, one or more layers of magnetic materials, and othermaterials (including magnetic and/or non-magnetic) now known or laterdeveloped. Such materials and/or structures may be arranged in anycombination or permutation now known or later developed.

The MTJ-based magnetoresistive stack/structure may include out-of-planemagnetic anisotropy or in-plane magnetic anisotropy. The presentinventions are applicable to all forms or types of magnetoresistivestacks/structures. Moreover, the free magnetic region may be disposed onthe magnetic tunnel barrier or beneath the magnetic tunnel barrier; thefixed magnetic region would be disposed on and interface a side of themagnetic tunnel barrier which is opposite to the side that interfacesthe free magnetic region.

Further, although the exemplary embodiments are described and/orillustrated above in the context of MTJ stacks/structures having a freemagnetic region disposed above the tunnel barrier and the fixed magneticregion disposed below the tunnel barrier, the present inventions may beimplemented wherein the fixed magnetic region is disposed above thetunnel barrier and the free magnetic region disposed below the tunnelbarrier. In this embodiment, the free magnetic region is formed on (andin contact with) the seed region. For the sake of brevity, theembodiment where the free magnetic region is formed on and in contactwith the seed region will not be separately illustrated —but theseinventions are to be interpreted as entirely applicable to suchembodiments where the free magnetic region is formed and disposed on theseed region (rather than formed and disposed on a dielectric material inthe case of MTJ stacks/structures). As such, in one embodiment, themagnetoresistive stack/structure includes an out-of-plane magneticanisotropy (for example, perpendicular magnetic anisotropy) where apinned or unpinned fixed magnetic region is disposed on or above one ormore layer(s) of dielectric material, which is disposed on or above afree magnetic region wherein the free magnetic region is disposed on andin contact with the seed region (which may be disposed on and in contactwith one or more layers of electrically conductive materials.

Although the described exemplary embodiments disclosed herein aredirected to various magnetoresistive-based devices and methods formaking such devices, the present disclosure is not necessarily limitedto the exemplary embodiments, which illustrate inventive aspects thatare applicable to a wide variety of semiconductor processes and/ordevices. Thus, the particular embodiments disclosed above areillustrative only and should not be taken as limitations, as theembodiments may be modified and practiced in different but equivalentmanners apparent to those skilled in the art having the benefit of theteachings herein. Accordingly, the foregoing description is not intendedto limit the disclosure to the particular form set forth, but on thecontrary, is intended to cover such alternatives, modifications andequivalents as may be included within the spirit and scope of theinventions so that those skilled in the art should understand that theycan make various changes, substitutions and alterations withoutdeparting from the spirit and scope of the inventions in their broadestform.

Notably, reference herein to “one embodiment” or “an embodiment” meansthat a particular feature, structure, or characteristic described inconnection with the embodiment may be included, employed and/orincorporated in one, some or all of the embodiments of the presentinventions. The usages or appearances of the phrase “in one embodiment”or “in another embodiment” in the specification are not referring to thesame embodiment, nor are separate or alternative embodiments necessarilymutually exclusive of one or more other embodiments, nor limited to asingle exclusive embodiment. The same applies to the term“implementation.” The present inventions are neither limited to anysingle aspect nor embodiment thereof, nor to any combinations and/orpermutations of such aspects and/or embodiments. Moreover, each of theaspects of the present inventions, and/or embodiments thereof, may beemployed alone or in combination with one or more of the other aspectsof the present inventions and/or embodiments thereof. For the sake ofbrevity, certain permutations and combinations are not discussed and/orillustrated separately herein.

Further, as indicated above, an embodiment or implementation describedherein as “exemplary” is not to be construed as preferred oradvantageous, for example, over other embodiments or implementations;rather, it is intended convey or indicate the embodiment or embodimentsare example embodiment(s).

In the claims, the term “ferromagnetic material” means or includesmagnetic and/or ferromagnetic materials. As noted above, the term“deposit” (or various forms thereof (e.g., deposited, deposition ordepositing)) means or includes deposit, grow, sputter, evaporate, formand/or provide (or various forms thereof). Moreover, in the claims,values, limits and/or ranges of the thickness and atomic composition of,for example, the seed region, means the value, limit and/or range+/−10%. The term “magnetoresistive stack”, in the claims, means orincludes a magnetoresistive stack or magnetoresistive structure, forexample, a magnetoresistive memory stack/structure (such as a memorycell in, for example, MRAM or the like) or a magnetoresistivesensor/transducer stack/structure (such as, for example, a read head forhard disk drives or the like).

The terms “comprise,” “include,” “have” and any variations thereof (forexample, “comprising,” “including” and “having”) are used synonymouslyto denote or describe non-exclusive inclusion. As such, a process,method, article and/or apparatus that uses such terms to, for example,describe a recipe, configuration and/or contents, does not include onlythose steps, structures and/or elements but may include other steps,structures and/or elements not expressly identified, listed or inherentto such process, method, article or apparatus.

Further, the terms “first,” “second,” and the like, herein do not denoteany order, quantity, or importance, but rather are used to distinguishone element from another. Moreover, the terms “a” and “an” herein do notdenote a limitation of quantity, but rather denote the presence of atleast one of the referenced item.

1-22. (canceled)
 23. A magnetoresistive stack comprising: a seed regiondisposed at least partially on an electrically conductive material,wherein the seed region includes: a plurality of alloy layers, whereineach alloy layer of the plurality of alloy layers includes nickel andchromium; and a plurality of auxiliary layers; a fixed magnetic regiondisposed above the seed region, wherein the fixed magnetic regionincludes a synthetic antiferromagnetic structure comprising: a firstferromagnetic region disposed above the seed region; a coupling layerdisposed on and in contact with the first ferromagnetic region; and asecond ferromagnetic region disposed on and in contact with the couplinglayer; one or more dielectric layers disposed on and in contact with thesecond ferromagnetic region; and a free magnetic region disposed abovethe one or more dielectric layers.
 24. The magnetoresistive stack ofclaim 23, wherein the fixed magnetic region is disposed on and incontact with the seed region.
 25. The magnetoresistive stack of claim24, wherein the fixed magnetic region is disposed on an auxiliary layerof the plurality of auxiliary layers.
 26. The magnetoresistive stack ofclaim 23, wherein at least one alloy layer of the plurality of alloylayers has a combined nickel content and chromium content of at least 99atomic percent.
 27. The magnetoresistive stack of claim 23, wherein eachalloy layer of the plurality of alloy layers has a thickness of 10 Å to25 Å.
 28. The magnetoresistive stack of claim 23, wherein the seedregion has a thickness greater than or equal to 30 Å.
 29. Themagnetoresistive stack of claim 23, further comprising a dusting layerdisposed between the seed region and the fixed magnetic region, whereinthe dusting layer includes at least one of molybdenum, magnesium, iron,platinum, ruthenium, an alloy including cobalt and iron, or combinationsthereof.
 30. The magnetoresistive stack of claim 29, wherein the dustinglayer has a thickness of 1 Å to 12 Å.
 31. The magnetoresistive stack ofclaim 23, wherein an alloy layer of the plurality of alloy layersincludes at least 30 atomic percent chromium.
 32. A magnetoresistivestack comprising: a seed region disposed at least partially on anelectrically conductive material, wherein the seed region includes: atleast one alloy layer, wherein the at least one alloy layer includesnickel and chromium and the content of other elements in the at leastone alloy layer is less than or equal to 1 atomic percent; and at leastone auxiliary layer; a dusting layer disposed on the seed region,wherein the dusting layer comprises molybdenum, magnesium, iron,platinum, ruthenium, an alloy including cobalt and iron, or acombination thereof; a fixed magnetic region disposed above the dustinglayer, wherein the fixed magnetic region includes a syntheticantiferromagnetic structure comprising: a first ferromagnetic regiondisposed above the dusting layer; a coupling layer disposed on and incontact with the first ferromagnetic region; and a second ferromagneticregion disposed on and in contact with the coupling layer; one or moredielectric layers disposed on and in contact with the secondferromagnetic region; and a free magnetic region disposed above the oneor more dielectric layers.
 33. The magnetoresistive stack of claim 32,wherein the at least one alloy layer is a first alloy layer and the seedregion further comprises a second alloy layer.
 34. The magnetoresistivestack of claim 32, wherein the at least one auxiliary layer is a firstauxiliary layer and the seed region further comprises a second auxiliarylayer.
 35. The magnetoresistive stack of claim 32, wherein the at leastone alloy layer has a thickness of 10 Å to 25 Å; and the dusting layerhas a thickness of 1 Å to 12 Å.
 36. The magnetoresistive stack of claim32, wherein the at least one alloy layer includes greater than or equalto 30 atomic percent chromium.
 37. The magnetoresistive stack of claim32, wherein the dusting layer includes an alloy including cobalt, iron,and boron.
 38. The magnetoresistive stack of claim 32, wherein the firstferromagnetic region comprises at least one of nickel, cobalt, orplatinum.
 39. The magnetoresistive stack of claim 32, wherein the atleast one auxiliary layer is disposed at least partially on theelectrically conductive material.
 40. A method of manufacturing amagnetoresistive stack, the method comprising: depositing a seed region,including: depositing at least one alloy layer including nickel andchromium; and depositing an auxiliary layer; depositing a fixed magneticregion, including a synthetic aniferromagnetic structure, above the seedregion, wherein depositing the synthetic antiferromagnetic structurecomprises: depositing a first ferromagnetic region above the seedregion; depositing a coupling layer on and in contact with the firstferromagnetic region; and depositing a second ferromagnetic region onand in contact with the coupling layer; depositing one or moredielectric layers above the second ferromagnetic region; and depositinga free magnetic region above the one or more dielectric layers.
 41. Themethod of claim 40, further comprising depositing a dusting layer,wherein the dusting layer is disposed between the seed region and thefixed region.
 42. The method of claim 40, wherein the combined nickelcontent and chromium content of the at least one alloy layer is at least99 atomic percent.